According to technical specification of 3GPP TS 36.211, the frame structure of a long term evolution (LTE) time division duplex (TDD) system is as shown in FIG. 1. The length of one radio frame is Tf=307200 Ts=10 ms, including two half-frames with the length being 5 ms, wherein each half-frame is composed of 5 subframes of which the length is 1 ms. The uplink-downlink configuration supported by the frame structure is as shown in table 1, wherein D represents that that a subframe is used for downlink transmission, U represents that the subframe is used for uplink transmission, and S represents a special subframe which contains three special time slots, wherein the three special time slots respectively are: a downlink pilot time slot (DwPTS) for downlink transmission, a guard period (GP) and an uplink pilot time slot (UpPTS) for uplink transmission.
TABLE 1Uplink-Downlink-downlinkto-uplinkconfig-Switch-pointSubframe numberurationperiodicity012345678905 msDSUUUDSUUU15 msDSUUDDSUUD25 msDSUDDDSUDD310 ms DSUUUDDDDD410 ms DSUUDDDDDD510 ms DSUDDDDDDD65 msDSUUUDSUUD
At present, in an LTE TDD system, the base station (for example, an evolved node B, i.e. eNodeB, referred to as eNB) of each cell sends uplink-downlink configuration information to terminals through a broadcast message. In order to control inter-cell interference, the base station of each cell usually uses the same uplink-downlink configuration. Therefore, when performing downlink transmission, a base station is mainly affected by the interference generated by downlink transmission of other base stations; and when performing uplink transmission, a terminal is mainly affected by the interference generated by uplink transmission of terminals in other cells.
TDD eIMTA (enhanced Interference Management and Traffic Adaptation, eIMTA) allows a base station to flexibly adjust uplink-downlink configuration according to the traffic load variation of the serving cell. When base stations of different cells have different uplink-downlink configurations, the interference on different subframes when a base station performs downlink transmission or a terminal performs uplink transmission may have significant variations. For example, as shown in FIG. 2(a), an eNB1 respectively uses uplink-downlink configuration Config. 0 (configuration 0) and Config. 2 in Radio frame #1 (Radio frame 1) and Radio frame #2; while as shown in FIG. 2(b), an eNB2 respectively uses uplink-downlink configuration Config. 2 and Config. 1 in Radio frame #1 and Radio frame #2. Therefore, when the eNB2 performs downlink transmission in subframes 0/1/5/6 of Radio frame #1 and subframe 0/1/4/5/6/9 of Radio frame #2, the downlink transmission performed by the eNB2 will be affected by the interference of the downlink transmission performed by the eNB1 in corresponding subframes; likewise, when the eNB2 performs downlink transmission in subframes 3/4/8/9 of the Radio frame #1, the downlink transmission performed by the eNB2 will be affected by the interference of uplink transmission performed by a terminal in a eNB1 service cell. Therefore, when the eNB2 performs downlink transmission, the interference situation on subframes 3/4/8/9 of Radio frame #1 may be significantly different from the interference situations on subframes 0/1/5/6 of Radio frame #1 and subframe 0/1/4/5/6/9 of Radio frame #2. The interference situations on subframes 3/4/8/9 of Radio frame #1 are relevant to the factors such as an uplink transmission power of a terminal in the interference source cell, and/or a distance between the terminal in the interference source cell and the terminal in the interfered cell.
An LTE system supports performing interference measurement by configuring a channel state information interference measurement resource (for example, a channel state information-interference measurement resource, referred to as a CSI-IM resource, which is configured based on a zero-power channel state information reference signal) so as to obtain a measurement and report of CSI. For example, as shown in FIG. 3, the uplink-downlink configurations of eNB1 and eNB2 are the same as that in FIG. 2; the eNB2 configures a set of CSI-IM resources (i.e. I in FIG. 3) on subframes 0 and 5 of each radio frame for a terminal to execute interference measurement with a period of 5 ms to acquire interference information containing interference generated by eNB1 downlink transmission, so as to acquire and report the CSI reflecting a channel situation for link adaptation transmission.
Or, as shown in FIG. 4, the uplink-downlink configurations of the eNB1 and eNB2 are the same as that of FIG. 2; the eNB2 configures two sets of CSI-IM resources (i.e. I1 and I2 in FIG. 4) on subframes 0 and 5 of each radio frame for the terminal to execute interference measurement with a period of 5 ms; the eNB1 also configures a CSI-IM resource at a time-frequency resource location which is the same as that of the first set of CSI-IM resources configured by the eNB2, and in this way, a terminal acquiring a service from the eNB2 may acquire, through the first set of CSI-IM resources, interference information not containing the interference generated by eNB1 downlink transmission, and acquire, through the second set of CSI-IM resource, interference information containing interference generated by eNB1 downlink transmission, so as to acquire and report two sets of CSI reflecting different channel situations for link adaptation transmission or coordinated multi-point transmission.
However, in TDD eIMTA, acquiring CSI through the above-mentioned CSI measurement and report method cannot effectively reflect the significant variations of the interference on different subframes in which a base station performing downlink transmission when a base station of a cell flexibly adjusts uplink-downlink configuration. For example, the configuration period of the CSI-IM resource in the related art is a multiple of 5 ms, and limited to this, the above-mentioned CSI measurement and report method cannot acquire CSI reflecting the interference situation on subframes 3/4/8/9 of the Radio frame #1 in which eNB2 performs downlink transmission as shown in FIG. 2 at the same time.
Another existing problem is that the change of uplink-downlink configuration used by a base station will cause the change of the transmission direction of a subframe configured with a channel state information-interference measurement resource by the base station, then if the terminal does not judge the transmission direction of the subframe to learn whether the subframe where the channel state information-interference measurement resource is located is a downlink subframe, a situation that the terminal performs interference measurement on a non-downlink subframe may happen, thereby causing the terminal executing an interference measurement operation on the subframe to be failed or an acquired interference measurement result to be inaccurate.
Aiming at the above-mentioned problems, no effective solution has been presented at present.